JP5863986B2 - Avoiding call disconnection during a radio link failure - Google Patents

Description

  The present invention relates to connection restoration within a mobile communication network.

  A handover is a voice call, video call, or any kind of user data exchange from a serving cell, also referred to as a source cell, to a new, more suitable cell, also referred to as a target cell, A process for transferring an ongoing wireless communication session. For example, when a mobile station moves away from the serving cell coverage area, the radio signal from that serving cell becomes weaker, while the radio signal from another more suitable cell becomes stronger. When the difference in received signal power between the two cells exceeds a predetermined threshold, a handover towards a more suitable cell is triggered.

  In Long Term Evolution (LTE) mobile networks, an overview of handover procedures and associated message exchange was introduced in June 2009 in the 3rd Generation Partnership Project (3GPP: 3rd Generation). “Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal TIR: Developmental Radio Access Network (E-UTRA) and Evolved Universal Terrestrial Traffic Network (E-UTRA). ation), 3GPP TS 36.300 v9.0.0, described in § 10.1.2.

  In a first step, the source evolution-Node B (eNB: evolved-NodeB) configures a measurement policy for the user equipment (UE), eg, the UE periodically and / or handovers A measurement report (MEASUREMENT REPORT) is configured to be sent as soon as an event is detected. The measurement reporting period and / or handover parameters for detecting the handover state are transmitted by the serving eNB.

  In a second step, the source eNB hands off the UE based on measurement report message (s) received from the UE and / or based on radio resource management (RRM) criteria. Make a decision. The source eNB directly issues a handover request (HANDOVER REQUEST) message to the target eNB, or as a handover request message, to a mobility management entity (MME) relayed toward the target eNB Either a HANDOVER REQUIRED message is issued and necessary information is passed to prepare for handover on the target side, including the UE signal context and UE data service context.

  In the third step, the target eNB configures the required radio resources and optionally reserves a Random Access Channel (RACH) preamble. The target eNB returns a handover request acknowledgment (HANDOVER REQUEST ACKNOWLEDGEMENT) message directly to the source eNB, or a handover request to the MME relayed toward the source eNB as a handover command (HANDOVER COMMAND) message. Acknowledge the handover request by either returning an acknowledgment message. The handover request acknowledgment message or the handover command message is a radio resource control (RRC) container to be passed transparently to the UE by the source eNB, that is, an RRC connection reconfiguration (RRC CONNECTION RECONFIGURATION) message. Contains.

  In the fourth step, the UE receives the RRC connection reconfiguration message with the necessary communication parameters and switches to the target cell. The UE synchronizes to the target eNB when a dedicated RACH preamble is reserved, according to a contention-free procedure, or according to a contention-based procedure if no dedicated preamble is indicated And access the target cell via the RACH.

  In the fifth step, the target eNB responds with the uplink allocation and the timing advance value. When the UE is successfully accessing the target cell, the UE sends an RRC CONNECTION RECONFIGURATION COMPLETE message to the target eNB. The target eNB can now send data to the UE and receive data from the UE.

  In the sixth and final step, the target eNB notifies the source eNB about the success of the handover procedure by sending a UE Context RELEASE message, which UE context release message Trigger release of radio resources by the eNB.

  In the case of non-optimal handover parameter settings, high loads in surrounding cells, or fast fading situations (eg tunnel roads), handover signaling messages may be lost. For example, a measurement report message sent by a UE immediately after detection of a handover condition may not reach the source eNB, which means that the target eNB is not ready to accept this UE doing. Further, for example, the UE may not receive a handover command message sent by the source eNB, but the target eNB is nevertheless ready to resume communication with this UE when necessary. ing.

  A Radio Link Failure (RLF) procedure as described in TS 36.300, § 10.1.6, allows the UE to resume communication with a ready eNB, It means an eNB that has been allowed to enter the UE during the handover execution phase that was performed previously.

  If the received signal exceeds the RLF threshold and the radio connection with the serving eNB is lost, then during the first phase, the UE first communicates with the serving cell of the serving eNB. Try to resume. If so, communication resumes as if no radio problems occurred. If the UE is unable to resume communication with the serving cell during the first phase, then the UE enters the RLF state and also during the second phase to the target cell or the best Attempts to connect to another cell providing radio link quality, eg, to another cell of the serving eNB, using a RRC CONNECTION REESTABISHMENT REQUEST message.

In the second phase, the following procedure is applied to resume activity and to avoid experiencing RRC_Idle. That is,
-The UE remains in the RRC_connection.
-The UE accesses the cell through a random access procedure.
-UE identifier used in the random access procedure for contention resolution, ie RLF done + Physical Cell Identity (PCI) + Encryption of the serving cell The cell radio network temporary identifier (C-RNTI) of the UE in the serving cell in case of a short message authentication code based on key (short MAC-I) is selected by the selected eNB Used to authenticate a UE and check if it has a context stored for that UE.
-If the eNB finds a context that matches the identity of the UE, i.e. the ENB is ready for that UE, the RRC connection may be resumed.
-If no context is found, i.e. if the ENB is not ready for the UE, the current RRC connection is released and the UE returns to the RRC_Idle state (i.e. the call is disconnected) )

“Evolved Universal Terrestrial Reverend (Third Generation Partnership Project)” published in June 2009 by the 3rd Generation Partnership Project (3GPP: 3rd Generation Partnership Project) (E-UTRA). Technical Specification (TS) 3GPP TS 36.300 v9.0.0 § 10.1.2 TS 36.300 § 10.1.6

  It is an object of the present invention to improve the success rate of connection restoration procedures inside mobile communication networks.

  According to a first aspect of the present invention, a radio resource control apparatus for controlling radio resources of a serving radio access node is provided for a radio communication session established between a serving radio access node and a specific mobile station. It is configured to allocate specific radio resources of the serving radio access node.

  The radio resource controller is further configured to push session information of the radio communication session to a common data repository accessible to the additional radio resource controller that controls radio resources of the additional radio access node. . The session information includes a mobile identifier that can be used by a particular mobile station for resumption of a wireless communication session, and the session information is further for wireless communication with a particular mobile station during the wireless communication session. , Allowing retrieval of contextual communication parameters used by the serving radio access node.

  According to a second aspect of the present invention, a method for controlling radio resources of a serving radio access node serves for a radio communication session established between the serving radio access node and a particular mobile station. Allocating specific radio resources of the radio access node.

  The method further includes pushing the session information of the radio communication session to a common data repository accessible to the further radio resource controller that controls the radio resources of the further radio access node. The session information includes a mobile identifier that can be used by a particular mobile station for resumption of a wireless communication session, and the session information is further for wireless communication with a particular mobile station during the wireless communication session. , Allowing retrieval of contextual communication parameters used by the serving radio access node.

  According to a third aspect of the present invention, a radio resource control device for controlling radio resources of a radio access node is configured to receive a reconnection request, whereby a specific mobile station can serve as a serving radio. It is configured to attempt to resume a previously established wireless communication session with the access node and to decode the mobile identifier of a particular mobile station from the reconnection request.

  The radio resource controller further determines the context communication parameters used by the serving radio access node for radio communication with a particular mobile station during a radio communication session when there is no context information associated with the mobile identifier. It is configured to query a common data repository using a mobile identifier for searching and to resume a wireless communication session with a specific mobile station using the communication parameters so searched Yes.

  According to a fourth aspect of the present invention, a method for controlling radio resources of a radio access node is the step of receiving a reconnection request, whereby a particular mobile station has previously communicated with a serving radio access node. Receiving and attempting to resume a wireless communication session established at a time, and decoding a mobile identifier of a particular mobile station from the reconnection request.

  The method retrieves context communication parameters used by a serving radio access node for radio communication with a particular mobile station during a radio communication session in the absence of context information associated with the mobile identifier. Querying a common data repository using the mobile identifier and resuming a wireless communication session with a particular mobile station using the communication parameters so retrieved.

  In accordance with a fifth aspect of the present invention, a radio resource control configuration comprises a computer platform configured to operate a radio resource control device and a further radio resource control device as two respective process instances. The computer platform further maintains a common data repository.

  In one embodiment of the invention, the serving radio access node pushes session information to a common data repository shortly after establishing a radio communication session with a particular mobile station.

  In one embodiment of the present invention, the serving radio access node pushes session information to a common data repository shortly after detecting a handover condition for a particular mobile station.

  In one embodiment of the present invention, the radio resource controller and the further radio resource controller share a common address space, and the session information includes a memory pointer that points to a memory area of the common address space. In addition, the context communication parameters are stored by the radio resource controller.

  Towards a general-purpose computer platform, it provides comprehensive radio access node functions that are not fixed to specific hardware and not tied to specific latency requirements, such as radio resource control and radio access node management, among others. It is assumed to be moved. The computer platform can comprise multiple computers and can include any type of processor or computer configuration that provides a single virtual execution environment (cloud computing).

  Each physical radio access node then runs on a computer platform and includes a corresponding virtual function that includes the comprehensive functions described above by example for each node as a specific process instance. It will be controlled remotely by the radio access node. This scheme allows for a reduction in equipment size for radio access nodes, and reduces capital and operational costs (CAPEX and OPEX), as well as the ecological footprint of mobile communication networks.

  Using this concept, in contrast to current network deployments with individual radio access nodes, each with its own baseband processing, user plane processing, and control plane processing. Pooling is possible.

  As soon as the handover state is performed for a particular UE, the UE context is pushed to a common database that is accessible to all virtual eNBs running on that computer platform. The UE context allows the UE to restore RRC connection, if any (eg C-RNTI + PCI + short MAC-I in the serving cell), number of radio bearer connections and individual characteristics, etc. Contains a UE identifier that can be used. The database thus maintains the UE context for all UEs for which the handover procedure is in progress. The UE context is deleted from the database as soon as the handover procedure is successfully completed and / or after some aging timer expires.

  Alternatively, and depending on the memory capacity of the computer platform, the UE context may be pushed once the UE enters the RRC_connected state, which means that the database for all active UEs It means to keep the UE context.

  If the UE tries to resume RRC connection with a further eNB following RLF, then the corresponding virtual eNB queries the database with the UE identifier supplied by the UE during the reconnection procedure. And even if the further eNB is not ready for that UE by the serving eNB, it fetches the corresponding UE context. Therefore, even an unprepared eNB can resume communication with its UE.

  This database can in principle be very small in terms of memory and processing power, since only pointers to the UE context need only be stored. The pointer tracks towards each UE context stored by each serving eNB.

  The above and other objects and features of the invention will become more apparent and the invention itself will be best understood by reference to the following description of one embodiment, taken together with the accompanying drawings. Will.

1 is a diagram representing an LTE mobile communication network. FIG. 1 represents an optical-wireless platform according to the invention. FIG. 4 is a plot of received signal power for a UE moving from one cell to another. FIG. 4 is a diagram illustrating a message flow chart for a handover failure in which radio connection recovery with an unprepared eNB continues according to the present invention.

The following network elements:
-ENB 10,
-MME 20;
-Serving Gateway (S-GW) 30, and
A packet data network (PDN) gateway (P-GW) 40;
A part 1 of an Evolved Radio Access Network (E-RAN) with UE 60 and an Evolved Packet Core (EPC) is shown in FIG.

  eNB 10 is coupled to MME 20 through the S1-MME interface and to S-GW 30 through the S1-U interface. S-GW 30 is further coupled to P-GW 40 through the S5 interface. P-GW 40 is further coupled to PDN 50 through an SGi interface. Adjacent eNBs 10 establish adjacency relationships through the X2 interface.

  The eNB 10 operates a macro cell, a micro cell, or a pico cell having a radio coverage area extending from several kilometers to several tens of meters. eNB 10 is configured to set up and operate a radio communication channel (ie, a set of downlink traffic radio resources and uplink traffic radio resources) using UE 60 through the Uu radio interface. .

More notably, each eNB 10 has the following functions:
-Radio resource control (RRC): radio bearer control, radio admission control, connection mobility control, dynamic allocation (scheduling) of resources for UEs in both uplink and downlink,
-Routing of user plane data towards the S-GW,
-Scheduling and transmission of paging messages from the MME;
-Scheduling and transmission of broadcast information;
-Host measurements and measurement report configuration for mobility and scheduling.

The MME 20 has the following functions:
-Non-Access Stratum (NAS) signal,
-Idle mode UE reachability, including control and execution of paging retransmissions;
-Tracking Area (TA) list management for UEs in idle mode and active mode,
-S-GW selection,
-MME selection for inter-MME handover,
-Roaming,
-Authentication,
– Host bearer management functions including dedicated bearer establishment.

S-GW 30 has the following functions:
-Local mobility anchor point for inter-eNB handover,
-E-UTRAN idle mode downlink packet buffering and initiation of network-triggered service request procedure;
-Lawful intercept,
-Packet routing and forwarding,
-Transport level packet marking on the uplink and downlink,
Hosts downlink and uplink charging per UE, PDN, and Quality of Service (QoS) class identifier (QCI).

The P-GW 40 has the following functions:
-UE IP address assignment, and IP anchor point,
-Per-user packet filtering (eg, using deep packet inspection),
-Lawful intercept,
-Hosts downlink and uplink service level billing, gating and rate enforcement.

  Further details about the optical wireless platform according to the present invention are shown in FIG.

  As in an exemplary embodiment, the optical wireless platform is shown to comprise two eNBs. The eNB is divided into two functional parts 100 and 200. The first part 100 further referred to as a physical eNB comprises an embedded eNB function that is operated inside the radio access node equipment close to the antenna, whereas the second part further referred to as a virtual eNB. Portion 200 comprises a generic eNB function that runs on the generic computer platform 300 as a respective process instance.

Each physical eNB 100 includes, among other things, the following functions:
One or more transceivers 110, each transceiver comprising a digital baseband unit 111 (or BBU) and an analog bandpass unit 112 (or ANA);
A coupling unit 120 (or COUP);
Host a network termination unit 130 (or NTU) for connection to the PDN 400.

  The network termination unit 130 is bidirectionally coupled to the digital baseband unit 111, the digital baseband unit 111 is bidirectionally coupled to the analog bandpass unit 112, and the analog bandpass unit 112 is the coupling unit. The coupling unit 120 is coupled to an external antenna or an internal antenna 140.

Each virtual eNB 200 includes, among other things, the following functions:
-Radio Access Node Manager 210 (or MGT);
-Host the radio resource controller 220 (or RRC).

  The computer platform 300 further comprises a network termination unit 310 for connecting to the PDN 400. The physical eNB 100 is in peer-to-peer communication with each one of the virtual eNBs 200 through the PDN 400.

  The computer platform 300 further comprises a data repository 320 where UE contexts for all UEs in the handover process are maintained. Data repository 320 is accessible to all virtual eNBs of computer platform 300 for both read and write access.

  The computer platform 300 may be implemented using a so-called cloud computing paradigm, so that a set of processes, regardless of their actual physical location and details inside the cloud, It runs inside a single virtual execution environment. Cloud computing provides high scalability and resiliency for computer applications.

  The transceiver 110 is configured to establish and operate a radio communication channel with the UE under the control of the radio resource controller 220.

  The digital baseband unit 111 is for digitally processing received data symbols and transmitted data symbols. The digital baseband unit 111 implements the necessary suite of protocols for issuing, terminating or relaying data and control packets.

  The analog band pass unit 112 is for modulating, amplifying, and shaping the transmission signal that is finally supplied to the antenna 140, and amplifies the reception signal from the antenna 140 with as little noise as possible, It is for demodulating. The analog bandpass unit 112 may be merged with a digital baseband unit or may be moved closer to the antenna in a so-called remote radio head-end (RRH) configuration There is sex.

  The combining unit 120 is for combining and passing the transmission signal from the transceiver 110 toward the antenna 140, and for transmitting the reception signal from the antenna 140 toward the transceiver 110.

  Network termination units 130 and 310 may include appropriate medium access control (MAC) and physical transport (PHY) layers for connection to PDN 400, and appropriate input / output (I / O) inputs. / Output) accepts any frame sending logic to route incoming / outgoing frames towards the port.

  The radio access node manager 210 is for configuring and managing the eNB.

  The radio resource controller 220 transmits the downlink radio resources and uplink radio resources used by the transceiver 110 for radio communication over the air interface and the respective UEs, i.e. for the transfer of user traffic. For assigning and managing a set of time and / or frequency resources that are assigned to each radio access bearer (RAB).

  Radio resource management (RRM) is system level control of co-channel interference characteristics and other radio transmission characteristics in a mobile communication system. RRM is involved in strategies and algorithms for controlling parameters such as transmit power, channel allocation, handover criteria, modulation scheme, error coding scheme and the like. The goal is to utilize limited radio spectrum resources and radio network infrastructure as efficiently as possible.

  RRM is particularly important in systems that are limited by co-channel interference rather than by noise, for example, in networks composed of multiple adjacent access points that can reuse the same channel frequency.

  The purpose of RRM is therefore to maximize system spectral efficiency while guaranteeing a certain grade of service. The latter is due to co-channel interference, noise, attenuation caused by long distances, fading caused by shadowing and multipath, Doppler shift, and other forms of distortion. Involved in avoiding outages or malfunctions. The grade of service may also be affected by blocking due to admission control and scheduling deficiency or inability to guarantee the required QoS.

  A dynamic RRM scheme adaptively adjusts radio network parameters for traffic load, user location, QoS requirements, and so on. Dynamic RRM schemes are considered and improved system spectrum in wireless or mobile network design in terms of minimizing expensive manual cell planning and achieving more stringent frequency reuse patterns. Bring efficiency. By exchanging information between eNBs, some schemes are centralized, others are distributed, either in autonomous algorithms in eNBs and UEs, or coordinated algorithms. Yes.

  Examples of dynamic RRM schemes include power control algorithms, link adaptation algorithms, dynamic channel allocation (DCA) algorithms or dynamic frequency selection (DFS) algorithms, traffic adaptive handover, adaptive filtering ( For example, single antenna interference cancellation (SAIC), dynamic diversity schemes (eg, soft handover, beamforming, multiple-input multiple-output (MIMO) communication, and / or space-time coding) Phased array antenna), admission control, resource reservation multiple access scheme or Dynamic bandwidth allocation using a total of multiplexing, cognitive radio or the like.

  Radio resource controller 220 is further configured for the handover procedure to push UE identity and context information to data repository 320 for any UE in progress (in FIG. 2). (See “Write (UE_id; UE_ctx_ptr)”).

  The UE identity information includes a temporary UE identifier UE_id, if any, used for call resumption by the UE. The UE identifier UE_id includes the C-RNTI assigned to the UE by the serving eNB, the serving cell PCI, and the short MAC-I used in the serving cell. The UE context information includes a pointer UE_ctx_ptr that points to the memory area, where the actual UE context UE_ctx is stored and kept up to date by the serving eNB. The UE context UE_ctx includes, among other things, a UE X2 signal context reference, a UE S1 EPC signal context reference, and characteristics of the established RAB (s) for that UE.

  Alternatively, the radio resource controller 220 can push the entire UE context UE_ctx directly to the data repository 320, but this problem-solving approach is less memory efficient.

  The radio resource controller 220 is further configured to query the data repository 320 whenever a request for reconnection is received from the UE and context information is not available. The data repository 320 is queried with a temporary UE identifier UE_id supplied by the UE during the reconnection procedure and assigned by the previous serving eNB (see “Read (UE_id)” in FIG. 2). . The data repository 320 returns a pointer UE_ctx_ptr that tracks where the UE context UE_ctx for the UE identifier UE_id is stored and kept up-to-date by the previous serving eNB. The radio resource controller 220 then fetches the entire UE context UE_ctx directly from the memory area referenced by the pointer. If no context is found for that UE identifier, the data repository 300 returns a null pointer or the like.

  A plot of downlink received signal power (DL Rx Pwr) as measured over time (t) by a UE moving from the source cell coverage area to the target cell coverage area is shown in FIG. Has been.

  The received power as measured over time by the UE for the downlink reference signal transmitted at the first nominal transmit power level by the source eNB is plotted as a monotonic curve PRXMAX_DL1. The received power, as measured over time by the same UE, for the downlink signal transmitted by the target eNB at the second nominal maximum transmit power level is plotted as a dotted curve PRXMAX_DL2.

  The reference downlink received power level to achieve a certain SNIR and thus a certain QoS is plotted as the bottom straight line PRXREF_DL. The difference between PRXMAX_DL1 and PRXREF_DL represents the amount of downlink transmit power backoff PTXBCK_DL1 that can be applied by the source eNB to limit radio interference while achieving acceptable QoS. The difference between PRXMAX_DL2 and PRXREF_DL represents the amount of downlink transmit power backoff PTXBCK_DL2 that can be applied by the target eNB.

  When downlink communication is established between the source eNB and the UE, and when the UE moves away from the source eNB, then the downlink transmit power back-off PTXBCK_DL1 decreases and is some distance from the source eNB. Null, which means that the maximum transmit power to achieve the required QoS inside the source cell is reached. This distance corresponds to the maximum radio coverage reach of the source cell. Ideally, from this distance outward, the received SNIR begins to deteriorate and the communication session should be switched towards a more appropriate neighboring cell using a handover procedure. A handover should occur before the radio communication hits the RLF reference threshold RLF_THD beyond which it is no longer possible with the source eNB.

  When the difference in received power, PRXMAX_DL2−PRXMAX_DL1 exceeds a predetermined threshold HO_margin (HO_margin) for TTT seconds, a handover event A3 triggers the handover procedure towards the target cell. To the serving eNB (see MEAS_REP (UE> eNB) in FIG. 3). It takes some time X2_delay (X2_delay) for the target eNB to be prepared and for the UE to receive the handover command and switch to the target cell (HO_CMD in FIG. 3 (eNB> UE )).

  If signal fading is too fast, and if the signal falls below the RLF reference threshold RLF_THD, the UE may not be able to report a HO event, which means that the cell Means that no handover will occur, or the UE may not receive a handover command, which means that one or more target cells Although not prepared, it means that no handover occurs. In both cases, the UE should resume a communication session with the source eNB or with an additional eNB that provides the best radio signal quality using the RRC reconnection procedure.

  A message flow chart representing the most prominent signal exchange between UE UE1 and the three eNBs eNB1, eNB2, and eNB3 is shown in FIG. The three eNBs eNB1, eNB2, and eNB3 are implemented on a single optical radio platform as in FIG. 2, ie their radio resource controller and further general functions are on a common computer platform. Each of which operates as a virtual eNB, but their baseband processing portion and analog portion operate on the remote physical radio access node equipment. The computer platform further maintains a data repository for storing the UE context of all UEs in the handover process.

  Within the coverage area of the first serving cell C1 operated by the eNB eNB1, the UE UE1 establishes a radio communication session with the serving eNB eNB1. The serving cell C1 has PCI1 as a PCI and ECGI1 as an E-UTRAN cell global identifier (ECGI). After random access, UE UE1 starts exchanging signaling messages with eNB eNB1 to establish downlink RAB and uplink RAB for L1 transport of user traffic (FIG. 4). (Refer to “1. Call setup”). Then UE UE1 enters the RRC_connected state. Inside cell C1, UE UE1 is assigned a temporary UE identifier UE_id1, and UE UE1 has call text UE_ctx1.

  The eNB eNB1 further transmits an RRC connection reconfiguration message to the UE UE1, whereby the UE UE1 is configured using the ad hoc measurement policy, measurement_configuration (meas_config) (see “2. RRC connection reconfiguration (measurement_configuration) ”). More specifically, UE UE1 has a generic offset parameter to trigger event state A3, a hysteresis HYS to enter and leave event state A3, and an event before reporting the event to eNB eNB1. State A3 is configured with a handover event A3 (neighboring cell has a better offset than the serving cell) including a TTT period to be executed in the meantime.

  UE UE1 measures the signal strength and / or signal quality from neighboring cells and compares them with respective handover thresholds. When moving away from eNB1, UE UE1 leaves the radio coverage area of cell C1 and enters the radio coverage area of another cell C2. The cell C2 has PCI2 as PCI and ECGI2 as ECGI. UE UE1 detects the measured power of the C2 reference signal to execute state A3. As a result, and assuming that this state is executed in TTT seconds, UE UE1 sends a measurement report message for notifying handover event A3 towards target cell C2 to source eNB eNB1. (See “3. Measurement Report (PCI2, A3_Event)” in FIG. 4).

  Immediately thereafter, the serving eNB eNB1 determines whether to perform a handover for the UE UE1 from the source cell C1 towards the target cell C2 based on further RRM criteria (see “4. HO in FIG. 4). (See Decision).

  The source eNB eNB1 decides to hand over the UE UE1 toward the cell C2, and transmits a handover request message to the target eNB eNB2 that operates the cell C2 via the X2 interface (see “ 6. Handover request (see target = ECGI2, UE_id1, UE_ctx1).

  The handover request message is assigned by the EGCI ECGI2 of the target cell C2 and the source eNB eNB1 in the source cell C1 as prominent information elements (IE), and for resuming the call by the UE UE1 if any. It contains the temporary UE identifier UE_id1 used and the call context UE_ctx1 of the UE UE1 inside the source cell C1.

  While sending the handover request message, the source eNB eNB1 also sends the UE identifier UE_id1 and the pointer UE_ctx_ptr1 to the memory area in which the UE context UE_ctx1 is stored and held up to date by the source eNB eNB1. Push to the repository (see “5. Push UE_id1 + UE_ctx_ptr1 to the data repository” in FIG. 4).

  After resource admission control (see “7. Resource Admission Control” in FIG. 4), the target eNB eNB 2 reserves the necessary downlink RAB and uplink RAB, and also receives a handover request acknowledgment message. To the source eNB eNB1, and this message contains the RRC connection reconfiguration container to be passed transparently by the source eNB eNB1 to the UE UE1 as an RRC message. The RRC connection reconfiguration includes a new UE identifier UE_id2 assigned by the target eNB eNb2 and to be used by the UE UE1 within the target cell C2 (see “8. Handover request acknowledgment (RRC connection in FIG. 4)). Reconfiguration (UE_id2)) ”and“ 9. RRC connection reconfiguration (UE_id2) ”).

  Currently, due to fast signal fading, UE UE1 does not receive the RRC connection reconfiguration message, and also detects the RLF condition when it moves away from the source cell C1 ( (See “10. RLF detection” in FIG. 4).

  As a result, the UE UE1 and another cell C3 operated by another eNB eNB3 that is not currently prepared by the source eNB eNB1 to accept the UE UE1 with the radio cell that provides the best radio signal quality Try to resume communication.

  After the random access (see “11. RACH access” and “12. UL allocation + TA” in FIG. 4), the UE UE1 transmits an RRC connection restoration request message to the eNB eNB3. The message includes the UE identifier UE_id1 assigned by the source eNB eNB1 in the source cell C1 (see “13. RRC connection restoration request (UE_id1)” in FIG. 4).

  Since the UE context is not available for the UE UE1 inside the eNB eNB3, the eNB eNB3 queries the data repository using the UE identifier UE_id1 and also stores it by the UE context pointer UE_ctx_ptr1 and further by the eNB eNB1 (See “14. Search for UE_ctx1 from data repository using UE_id1” in FIG. 4). Therefore, the eNB 3 can accept the request for reconnection from the UE UE1, and responds using the RRC connection restoration message (see “15. RRC connection restoration” in FIG. 4). Eventually, UE UE1 responds with an RRC connection restoration complete message, and UE UE1 stays in the RRC_connected state, which means that the call is kept but eNB eNB3 is This means that the UE has not been prepared (see “16. RRC connection restoration complete” in FIG. 4).

  Also, if the UE UE1 is still attached to a further eNB eNB4 whose virtual eNB operates on the second optical radio platform, the virtual eNB eNB4 operates the virtual eNB that controls the source eNB eNB1 Request UE context from optical wireless platform database. The address of this database may be obtained from the PCI PCI1 of the source eNB eNB1 by querying the directory service or from locally configured data, for example. A remote database query may be sent to a dedicated port that supports a given set of message primitives and is open for all optical wireless platforms, for example.

  There may be a second database pointing to the context of all active UEs depending on the processing capacity and storage capacity of the optical wireless platform. If there is a coverage hole (eg tunnel, shadow from large building, wrong network plan), the UE will suffer RLF without being present in the handover procedure, ie received by the source eNB. There will be no measurement report message being sent. 3GPP defines this as a handover failure for a handover failure “too early” or “wrong cell”. As long as the second RLF phase is operational, the UE will send an RRC connection recovery request message, and in this case, the addressed eNB will also be all active inside the optical radio platform. The UE context is fetched from the database based on the pointer toward the correct UE. In this case, the call is not disconnected.

  Although the above description has made a thorough reference to LTE technology and terminology, the present invention relates to Global System Mobile (GSM), Code Division Multiple Access (CDMA), Equally useful for other mobile or wireless communication technologies, such as the Universal Mobile Terrestrial System (UMTS).

  It should be noted that the term “comprising” should not be construed as limited to only the means listed below. Therefore, the scope of the expression “a device comprising means A and B” should not be limited to only devices comprising only components A and B. That means, for the present invention, the relevant components of the device are A and B.

  It should further be noted that the term “coupled” should not be construed to be limited to direct connections only. Accordingly, the scope of the expression “device A coupled to device B” should not be limited to devices or systems where the output of device A is directly connected to the input of device B, and / or vice versa. It is the same. It means that there is a path between the output of A and the input of B and / or vice versa, this path can be a path that includes other devices or means Yes.

  The description and drawings merely illustrate the principles of the invention. Accordingly, those of ordinary skill in the art will implement the principles of the present invention and devise various configurations that fall within the spirit and scope thereof, although not explicitly described or shown herein. It will be understood that it will be possible. Moreover, all examples listed herein primarily assist the reader in understanding the principles of the invention and the concepts contributed by the inventor (s) to promoting the art. Should be expressly intended to be for educational purposes only and should not be construed as limited to such specifically listed examples and conditions. Moreover, all statements herein reciting principles, aspects, and embodiments of the invention, as well as specific examples thereof, are intended to encompass equivalent forms thereof.

  The functionality of the various elements shown in the drawings may be provided through the use of dedicated hardware as well as hardware capable of executing software in conjunction with appropriate software. When provided by a processor, their functionality is provided by a single dedicated processor, by a single shared processor, or by multiple individual processors, some of which may be shared. Sometimes. Further, a processor should not be construed to mean exclusively hardware capable of executing software, but also implicitly, without limitation, a digital signal processor (DSP) hardware. Hardware, network processor, application specific integrated circuit (ASIC), field programmable gate array (FPGA), and the like. Other hardware, such as read only memory (ROM), random access memory (RAM), non-volatile storage, whether conventional and / or custom, may also be included There is also.

Claims (5)

A radio resource control device (220a) for controlling radio resources of a serving radio access node (100a), wherein a radio communication session established between the serving radio access node and a specific mobile station Configured to allocate specific radio resources of the serving radio access node to
The radio resource controller is further accessible in read access and write access to both the radio resource controller (220b) and the radio resource controller, which controls radio resources of the further radio access node (100b). Configured to push session information (UE_id; UE_ctx_ptr) of the wireless communication session to a common data repository (320);
The session information includes a mobile identifier (UE_id) that can be used by the specific mobile station for resuming the wireless communication session, and the session information is further included during the wireless communication session. Enabling retrieval of context communication parameters (UE_ctx) used by the serving radio access node for radio communication with a mobile station ;
The radio resource controller is configured to operate on a computer platform with the additional radio resource controller;
The computer platform further maintains a common data repository and is remotely coupled to the serving radio access node and the further radio access node via a packet data network. ).   The radio resource controller (220a) according to claim 1, wherein the session information is pushed to the common data repository immediately after establishment of the radio communication session with the particular mobile station.   The radio resource controller (220a) according to claim 1, wherein the session information is pushed to the common data repository immediately after detection of a handover state for the particular mobile station. Before cinchona ray resource control apparatus and the further radio resource controller, share a common address space,
The session information may also, further comprises a memory pointer (UE_ctx_ptr) towards the memory area of a common address space, the context communication parameters are stored by the previous quinic ray resource control device, according to claim 1 Radio resource control device . A method for controlling radio resources of a serving radio access node (100a) , wherein a radio resource controller is configured to establish a radio communication session established between the serving radio access node and a specific mobile station. Allocating specific radio resources of said serving radio access node to
To a further radio resource controller (220b) that controls radio resources of the further radio access node (100b) and to a common data repository (320) accessible in read and write access to said radio resource controller Further comprising the step of the radio resource control device pushing session information (UE_id; UE_ctx_ptr) of the radio communication session;
The session information includes a mobile identifier (UE_id) that may be used by the particular mobile station for resuming the wireless communication session;
The session information also enables retrieval of context communication parameters (UE_ctx) used by the serving radio access node for radio communication with the specific mobile station during the radio communication session ,
The method includes operating the radio resource controller on a computer platform with the additional radio resource controller;
The computer platform further maintains a common data repository and is remotely coupled to the serving radio access node and the further radio access node via a packet data network .

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